A joystick is a well-known mechanical actuator for a device that can be used to provide control input to electronic games and computers. Another similar device is sometimes referred to as a directional control pad ("DCP"). A DCP generally has of an active area, usually circular, and is typically about one and one half inches in diameter. Application of pressure at various angular positions on the active area of a DCP produces a corresponding electrical output signal.
Most inexpensive controllers, of either the joystick or DCP type, provide only limited, coarse, output signals. This is due to the fact these devices generate their output signals by the use of four momentary switches. Typically, four leaf switches or conductive rubber dome switches are used for end point detection in each of four possible directions of motion of the actuator of the controller, e.g., "North", "South", "East" and "West" directions. In general, these switches are spaced 90 degrees from each other around the periphery of the input device. In these devices, a given amount of motion solely in the "North" direction, for example, causes the closure of only the single switch used to detect motion in this direction. The same is true for motions exclusively in the "South", "East", and "West" directions. Motion of the joystick in a "North-East" direction, can cause simultaneous closure of both the "North" and "East" switches. Likewise, dual switch closures will occur for joystick motion in the "North-West", "South-East", and "South-West" directions. Thus, there are only eight directions which can be represented by unique output states of such a simple device. Furthermore, in devices which use momentary switches, the output of the device merely indicates a switch being "on" or "off", and no output signal is generated which indicates the magnitude of the force being applied by the user in that direction.
One significant problem with the electromechanical devices as described above is that they are subject to an increase in the resistance of the switch contacts due to, for example, wear, misalignment, oxidation, and accumulation of dirt. As the contact resistance increases, the switch begins to fail on an intermittent basis. Intermittent failures of an input controller are particularly unacceptable in a game environment where split second reactions by a user are often required. Devices based upon mechanical switches also suffer from the inherent variations from one switch to another, such as the gap between contacts and spring stiffness. These variations will result in inconsistent and uneven position indication from the control device, and provide inadequate sensitivity for certain applications of the device. Additionally, mechanical switches are also subject to switch bounce in which the output of the switch will oscillate between its "on" and "off" voltages for several milliseconds after being switched.
It is therefore one object of the present invention to provide a practically infinite resolution of the angular direction of the motion or force applied to an input controller. It is an additional object of the present invention to indicate the amplitude of the motion or force applied in a specific direction to an input controller. It is also an object of the present invention to decrease the cost of producing an analog control device. It is a further object of the invention to increase the resilience of an input device to conventional wear. It is also an object of the present invention to construct a piezoresistive input device using a conductive foam.